What do you call it? Do you say Rear Derailleur, Rear Mech, Rear Mechanism, ‘Mech’ or just ‘Gears’… they are all names to describe the mechanism typically controlled by a spring and cable that derails the chain and moves that chain out of one gear and into the next. I’m sure everyone has their favourite model and I am no exception; I’ve never tried to hide my love of Shimano, so my all time favourite rear derailleur has to be the Shimano Dura-Ace 7400. Even though it has a simple job to fulfill, the introduction and continued innovation of the rear derailleur has always been at the forefront of bicycle technology and the RD-7400 was in my opinion the start of the modern technology revolution.